Cellulose ester wound dressing

ABSTRACT

A wound dressing that releases, via hydrolysis and in a controlled manner, acetic acid when subjected to body temperatures and moisture, and is made from a cellulose ester substrate with a partial solvent thereon.

This is a continuation of Ser. No. 08/496,701, filed Jun. 29, 1995, nowU.S. Pat. No. 5,685,832.

FIELD OF THE INVENTION

The invention is directed to a wound dressing that releases acetic acidin a controlled manner and that is made from a cellulose ester and apartial solvent.

BACKGROUND OF THE INVENTION

Wound dressings made of cellulose diacetate are known. See: People'sRepublic of China Patent Application No. 87 1 01823A published Aug. 31,1988. Therein, it is disclosed that a cellulose diacetate gauze wounddressing obtains beneficial results over conventional cotton gauze wounddressing because the inventive dressing does not stick to the wound.Additionally, Johnson & Johnson of New Brunswick, N.J., has marketed anon-adhering cellulose acetate, petrolatum emulsion impregnated wounddressing under the tradename "Adaptic" since Feb. 3, 1984.

Additionally, the medical advantages obtained by treating wounds withacetic acid (or vinegar) is widely known in folk medicine. See: G.Majno, "The Healing Hand Man and Wound in the Ancient World", HarvardUniversity Press, paperback edition, 1991, page 186. A combination ofvinegar and ethyl alcohol is also known to be beneficial for treatingwounds. See: PCT Application FR88/00238, published Nov. 17, 1988.Therein, a therapeutic solution of vinegar, distilled water, and ethylalcohol is used to treat burns.

The use of triacetin, trimethylene glycol diacetate, and glycolmonoethylene acetate on cellulose acetate tow is known. In this knownusage, triacetin, trimethylene glycol diacetate, and glycol monoethyleneacetate act as plasticizers that facilitate inter-filament bonding.

There is a need for a wound dressing that can release acetic acid in acontrolled manner, thereby facilitating wound healing.

SUMMARY OF THE INVENTION

A wound dressing that releases, via hydrolysis and in a controlledmanner, acetic acid when subjected to body temperatures and moisture,and is made from a cellulose ester substrate with a partial solventthereon.

DESCRIPTION OF THE DRAWINGS

For the purposes of illustrating the invention, there is shown in thedrawings information about the invention; it being understood, however,that this information is provided to illuminate the invention and not tolimit it.

FIG. 1 is a graphical representation of the release of acetic acid(milligrams (mg) acid per gram (g) dressing per day) as a function oftemperature (0° C.) from one embodiment of the present invention.

FIG. 2 is a graphical representation of the release of acetic acid(micrograms (mcg) acid per gram (g) cellulose acetate per day) as afunction of temperature (0° C.) from cellulose acetate having a degreeof substitution of about 2.5.

DETAILED DESCRIPTION OF THE INVENTION

"Wound dressing", as used herein, refers to a bandage or the like whichcovers and protects wounds, for example: abrasions, cuts or burns. Theinventive wound dressing is not impregnated with a petrolatum emulsion.

"Cellulose ester", as used herein, refers to organic esters. Examples ofsuch esters include: cellulose acetate; cellulose propionate; cellulosebutyrate; cellulose acetate propionate; cellulose acetate butyrate;cellulose propionate butyrate; and the like; and combinations thereof.The cellulose esters useful in the present invention can be prepared byany known technique. See: Kirk-Othmer, Encyclopedia of ChemicalTechnology, 3rd Edition, Vol. 5, John Wiley & Sons, New York, NY, 1979,p. 89-129; and Libscomb, A. G., Cellulose Acetate: Its Manufacture andApplications, Ernest Benn, Ltd. London, GB, 1933, both are incorporatedherein by reference. The cellulose esters of the present inventionpreferably have at least 2 anhydroglucose rings and most preferably havefrom about 2 to 5,000 anhydroglucose rings. Also, such polymerstypically have an inherent viscosity (IV) of about 0.2 to about 3.0deciliters per gram, most preferably about 1 to 1.6, as measured at atemperature of 25° C. from a 0.5 gram sample and 100 ml of a 60/40 byweight solution of phenol/tetrachloroethane. In addition, the DS/AGU(degree of substitution per anhydroglucose unit) of the cellulose estersuseful herein ranges from about 1.5 to about 2.7. Cellulose acetateshaving a DS/AGU of 1.7 to 2.6 are especially preferred. The mostpreferred cellulose acetate has a DS/AGU of 1.8 to 2.2 and an IV of 1.3to 1.5.

The foregoing cellulose esters may contain delustrants (e.g., titaniumdioxide) and spin finishes as is well known.

"Substrate", as used herein, refers to fabric (woven or knitted) or filmforms of cellulose esters and excludes tows or yarns unless in woven orknitted form. For example, the cellulose ester may be produced in astaple or filament form, then spun into yarns, and the yarns may bewoven or knitted into fabrics. Alternatively, the cellulose ester may beformed into a film. The film maybe porous, e.g., microporous. A gauze ispreferred.

"Partial solvent", as used herein, refers to, for example, glyceroltriacetate (also known as, triacetin), trimethylene glycol diacetate,glycol monoethyl ether acetate, and combinations thereof. Triacetin ispreferred. The solvent may be sprayed onto the cellulose estersubstrate. The solvent may comprise about 4-15% by weight of thesubstrate. Preferably, the solvent comprises about 10% by weight of thesubstrate.

"Body temperature and moisture" refers to the conditions that aretypically found at or around the wound, for example, the temperature ator around a wound of the human body may be about 98.6±5° F.

The present invention is able to release acetic acid, via hydrolysis, ina controlled manner. Specifically, the dressing releases acetic acid ata rate greater than 1000 micron grams per day. Preferably, the inventivewound dressing releases about 4 to 6 milligrams per day. FIG. 1illustrates that cellulose ester fibers (e.g. cellulose acetate,DS/AGU=2.5) with a partial solvent (i.e., triacetin) thereon, release agreat amount of acetic acid. FIG. 2 illustrates that untreated celluloseester fibers (e.g. cellulose acetate, DS/AGU=2.5) release minor amountof acetic acid.

The present invention is further explained with reference to thenon-limiting examples below.

EXAMPLES Example 1 (COMPARATIVE)

Cellulose acetate having a degree of substitution of approximately 2.5is heated to a constant temperature of 100° C. at a relative humidity ofnearly 100%. Hydrolysis of cellulose acetate under these conditionsyields approximately 400 micrograms per gram of cellulose acetate perday. Note: FIG. 2.

Example 2

At 10% by weight of triacetin (glycerol triacetate) is added to thecellulose acetate described in Example 1. The treated cellulose acetateis subjected to the same conditions as in Example 1. Approximately 4.5milligrams cellulose acetate/triacetin is formed for a day. Note: FIG.1.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specification, as indicating the scope of theinvention.

We claim:
 1. A wound dressing comprising a cellulose ester substrate anda partial solvent thereon, wherein said substrate is a knitted fabric,wherein said dressing releases, via hydrolysis of said cellulose esterat 98.6±5° F. and in a controlled manner, acetic acid.
 2. The dressingof claim 1 wherein the partial solvent is selected from the groupconsisting of: glycerol triacetate, trimethylene glycol diacetate,glycol monoethylene acetate, and combinations thereof.
 3. The wounddressing of claim 2 wherein the partial solvent is glycerol triacetate.4. The wound dressing according to claim 1 wherein the dressing releasesgreater than 1000 micrograms per day of acetic acid.
 5. The dressing ofclaim 1 wherein the cellulose ester is cellulose acetate having a degreeof substitution of about 2.5 per anhydroglucose unit.